How to prove the derivative of $a^{T} A^{-1} b$ with respect to $A$












2












$begingroup$


So I can find from the matrix cookbook here:



$frac{partial a^TX^{-1}b}{partial X} = -X^{-T}ab^TX^{-T}$



To prove it, I have tried expanding:



$a^TX^{-1}b = sumlimits_{i,j}^{n,n}a_i(X^{-1})_{ij}b_j$



I can also find from cookbook where:



$frac{partial (X^{-1})_{ij}}{partial X_{ij}} = -(X^{-1})_{ij}(X^{-1})_{ij}$



However, what I cannot figure out is that where did that transpose come from?



Any idea and help are appreciated!










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  • 1




    $begingroup$
    See here math.stackexchange.com/questions/3023692/…
    $endgroup$
    – user550103
    Dec 6 '18 at 6:30










  • $begingroup$
    Thank you very much for the referring. It is really helpful.
    $endgroup$
    – Wei
    Dec 6 '18 at 23:19
















2












$begingroup$


So I can find from the matrix cookbook here:



$frac{partial a^TX^{-1}b}{partial X} = -X^{-T}ab^TX^{-T}$



To prove it, I have tried expanding:



$a^TX^{-1}b = sumlimits_{i,j}^{n,n}a_i(X^{-1})_{ij}b_j$



I can also find from cookbook where:



$frac{partial (X^{-1})_{ij}}{partial X_{ij}} = -(X^{-1})_{ij}(X^{-1})_{ij}$



However, what I cannot figure out is that where did that transpose come from?



Any idea and help are appreciated!










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    See here math.stackexchange.com/questions/3023692/…
    $endgroup$
    – user550103
    Dec 6 '18 at 6:30










  • $begingroup$
    Thank you very much for the referring. It is really helpful.
    $endgroup$
    – Wei
    Dec 6 '18 at 23:19














2












2








2


1



$begingroup$


So I can find from the matrix cookbook here:



$frac{partial a^TX^{-1}b}{partial X} = -X^{-T}ab^TX^{-T}$



To prove it, I have tried expanding:



$a^TX^{-1}b = sumlimits_{i,j}^{n,n}a_i(X^{-1})_{ij}b_j$



I can also find from cookbook where:



$frac{partial (X^{-1})_{ij}}{partial X_{ij}} = -(X^{-1})_{ij}(X^{-1})_{ij}$



However, what I cannot figure out is that where did that transpose come from?



Any idea and help are appreciated!










share|cite|improve this question











$endgroup$




So I can find from the matrix cookbook here:



$frac{partial a^TX^{-1}b}{partial X} = -X^{-T}ab^TX^{-T}$



To prove it, I have tried expanding:



$a^TX^{-1}b = sumlimits_{i,j}^{n,n}a_i(X^{-1})_{ij}b_j$



I can also find from cookbook where:



$frac{partial (X^{-1})_{ij}}{partial X_{ij}} = -(X^{-1})_{ij}(X^{-1})_{ij}$



However, what I cannot figure out is that where did that transpose come from?



Any idea and help are appreciated!







matrices derivatives partial-derivative matrix-calculus






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 6 '18 at 6:41









AVK

2,0961517




2,0961517










asked Dec 6 '18 at 1:33









WeiWei

162




162








  • 1




    $begingroup$
    See here math.stackexchange.com/questions/3023692/…
    $endgroup$
    – user550103
    Dec 6 '18 at 6:30










  • $begingroup$
    Thank you very much for the referring. It is really helpful.
    $endgroup$
    – Wei
    Dec 6 '18 at 23:19














  • 1




    $begingroup$
    See here math.stackexchange.com/questions/3023692/…
    $endgroup$
    – user550103
    Dec 6 '18 at 6:30










  • $begingroup$
    Thank you very much for the referring. It is really helpful.
    $endgroup$
    – Wei
    Dec 6 '18 at 23:19








1




1




$begingroup$
See here math.stackexchange.com/questions/3023692/…
$endgroup$
– user550103
Dec 6 '18 at 6:30




$begingroup$
See here math.stackexchange.com/questions/3023692/…
$endgroup$
– user550103
Dec 6 '18 at 6:30












$begingroup$
Thank you very much for the referring. It is really helpful.
$endgroup$
– Wei
Dec 6 '18 at 23:19




$begingroup$
Thank you very much for the referring. It is really helpful.
$endgroup$
– Wei
Dec 6 '18 at 23:19










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